Animals maintained on fat-free diets develop deficiency symptoms which can be cured by administration of the essential fatty acids. The requirements for essential fatty acids at the cellular level can be examined conveniently using the technique of tissue culture. The characteristics of a number of diploid and heteroploid cell lines grown in chemically-defined medium in the absence of these compounds will be examined. The diploid human fibroblasts WI26 and WI38 produce dihomo-gamma-linolenic and arachidonic acids, the precursors of prostaglandins of the PG1 and PG2 series, in good yield from 14C-linoleic acid. When the cells are transformed by the oncogenic SV40 virus, this ability is lost. The relationship of these findings to the ability of cells to synthesize prostaglandins in tissue culture from 14C-labelled essential fatty acid precursors is being investigated. The second part of the project is related to continuing studies on the role of serum lipoproteins in regulating the cholesterol content of cells and tissues. When grown in serum medium cell cholesterol is derived almost entirely from the lipoproteins and de novo synthesis is repressed. Their function in cellular cholesterol transport is being studied using 125I-treated alpha and beta lipoproteins doubly-labelled with 3H-cholesterol. Studies on the permeability of aorta sacs to the radioactive lipoproteins will also be carried out. The relative contribution of the alpha and beta lipoproteins to cell cholesterol will be examined by growing cells in reconstituted lipoprotein mixtures and in serum obtained from lipoproteinemic patients. BIBLIOGRAPHIC REFERENCES: Anti-Inflammatory Drugs in Experimental Atherosclerosis II. Failure of Antihypertensive Drugs to Exacerbate Plaque Formation. J.M. Bailey and R.L. Randazzo. Atherosclerosis 26: 91, 1977. Lipid Metabolism in Cultured Cells XVI. Lipoprotein Binding and HMG CoA Reductase Levels in Normal and Tumor Virus Transformed Human Fibroblasts. J.M. Bailey and J.D. Wu. J. Lipid Res. in press, July 1977.